Zirconium phosphate is used in sorbent dialysis to remove waste and unwanted solutes including ammonium, potassium, calcium, and magnesium ions from dialysate. Zirconium oxide can be used to remove phosphate ions from dialysate. The zirconium phosphate and zirconium oxide are generally packaged in a sorbent cartridge. Usually, sorbent cartridges are discarded and replaced after use. The discarded sorbent cartridges are broken down and the zirconium phosphate and zirconium oxide are separated from the other sorbent materials. Because zirconium phosphate and zirconium oxide are expensive and rechargeable, sorbent re-processors treat the recovered materials with chemical solutions. The recycling process requires transporting the materials to reprocessing facilities and involves laborious recycling steps in addition to recharging the sorbent materials. Further, the sorbent material cannot be immediately reused, and must be added to a new sorbent cartridge and repackaged for sale. Conventional methods drive up costs and infrastructure requirements, and increase complexity and waste.
Different patients may require differing dialysate bicarbonate levels for effective treatment. For example, alkalotic patients require a dialysate bicarbonate level lower than other patients. The bicarbonate level of the dialysate is generally controlled by the addition sodium bicarbonate, which acts as a buffer. Bicarbonate ions in the dialysate are in equilibrium with carbon dioxide. The zirconium phosphate effluent pH is the main driver in determining the bicarbonate/carbon dioxide ratio. A lower zirconium phosphate effluent pH will produce more pCO2 which can result in dialysate entering the dialyzer at too low a pH, potentially causing hemolysis. High pCO2 can also cause bubbles to form in the dialysate which can potentially be transferred to the patient. The excess CO2 can be removed by a degasser, such as a membrane contactor degasser, a vacuum degasser, or any other device capable of removing CO2 from solution. A higher zirconium phosphate effluent pH will result in higher bicarbonate concentration, requiring less bicarbonate addition to the dialysate, but may not be usable in treatment of all patients.
Known recharging systems do not control the volume of chemical solutions used in recharging the zirconium phosphate and zirconium oxide, and instead simply treat the materials with enough recharging chemicals to ensure complete recharging. Complete recharging of the sorbent materials is generally used to cover worst case situations to avoid ammonia breakthrough in patients with high levels of urea or other ions. Complete recharging of the sorbent materials in each case is wasteful and more costly than recharging the sorbent materials only to the point necessary for a future dialysis session. Recharging zirconium phosphate or zirconium oxide in this fashion results in the use of higher volumes of recharging chemicals than may be necessary.
Hence, there is a need for systems and methods that can recharge zirconium phosphate in a zirconium phosphate sorbent module and/or zirconium oxide in a reusable zirconium oxide sorbent module in a precise and efficient manner. There is a need for systems and methods that can more precisely match a recharge process for zirconium phosphate and/or zirconium oxide with actual cartridge need and usage, thus eliminating extra expense, time, money, and chemical usage. There is also a need for systems and method that can customize the dialysate bicarbonate levels by controlling the zirconium phosphate effluent pH. There is further a need for systems and methods that can control the zirconium phosphate recharging process to create a zirconium phosphate module having a desired effluent pH. The need extends to systems and methods for determining a desired zirconium phosphate effluent pH based on the needs of the patient and system. There is also a need for systems and methods that can calculate the amount of recharging solutions necessary for recharging the zirconium phosphate and/or zirconium oxide.